#include<bits/stdc++.h>
using namespace std;
int f[20][20],n;
int main() {
	cin >> n;
	for(int i=0; i <= n; i++) {
		for(int j = 0; j <= n; j++) {
			if(!i) f[i][j] = 1;
			else if(!j) f[i][j] = f[i-1][j+1];
			else f[i][j] = f[i-1][j+1] + f[i][j-1];
		}
	}
	cout << f[n][0];
}

